Eighty subjects participated in a study with five age groups (20, 30, 40, 50, and 60 years). Forty subjects showed evidence of factors related to brain dysfunction (risk factors). Their performance on a Sternberg-type memory scanning task was assessed. Age-related slowing of virtually all aspects of the memory scanning process was observed in the healthy group. However, the effect of the presence of risk factors was larger than that of biological age. The results of the present study make a reasonable case for the view that many age effects reported in the literature can be largely explained by suboptimal brain functioning, i.e., by other factors than aging per se.
Houx, P. J., Vreeling, F. W., & Jolles, J. (1991). Rigorous health screening reduces age effect on memory scanning task. Brain and Cognition, 15(2), 246-260. https://doi.org/10.1016/0278-2626(91)90029-8